Scientists have found a link between children who go on to suffer from bipolar
disorder and mothers who have the flu while pregnant.

If the findings from the research, which suggests children are four times more likely to develop the disorder if their mothers suffer from the flu during their pregnancy, vaccination policies for mothers to be may have to be changed.

But women have been advised not to worry as the risk is still fairly low, and the study needs to be done with a larger sample before the link can be confirmed.

Scientists in South Africa and the US examined data from people born between 1959 and 1966 in the American Kaiser Permanente health system, matching their mother’s health records with later psychiatric assessments. It found of 92 people who were bipolar, eight had been exposed to flu while in the womb.

The journal JAMA psychiatry said: “Offspring exposed to maternal influenza infection at any time during pregnancy were nearly four times more likely to develop bipolar disorder than those who were not exposed.”

Scientists believe the flu can disrupt the development of the brain, and the disease has previously been linked to schizophrenia in children.

Dr Fiona Gaughran, consultant psychiatrist at the Maudsley Hospital, told The Times: “If future work confirms the link reported here, policy makers may need to consider implications for flu prevention pre-pregnancy, but mothers need not be worried. The overall risk of offspring developing bipolar disorder is low even if one did get flu in pregnancy.”

Experts have said around one per cent of the population develop bipolar disorder, so a four-fold increase in risk would still mean the likelihood of children developing the condition was low. Scientists also suggested there could be other risk factors involved, not just women having the flu while pregnant, and said the study needs to be repeated in a larger sample.